Device for converting calorific energy into mechanical energy

ABSTRACT

A device such as hot-gas engines, hot-gas turbine, and internal combustion engine for converting calorific energy into mechanical energy comprising at least one combustion chamber for hydrogen and at least one cooler incorporated in a system of ducts for cooling medium; the combustion chamber can be made to communicate with a hydrogen container containing an alloy of A and B, in which the ratio A:B can vary from 1:3 to 2:17 in powder form, where A is Ca or one or more of the elements of the rare earths, combined with Th and/or Zr and/or Hf, and where B is mainly Ni and/or Co. The hydrogen container and a part of the system of ducts are constructed for heat exchange between the alloy in the hydrogen container and the medium in the system of ducts.

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75 Inventor: R Jan M j Emmasingel 965,454 7/1964 Great Britain ...l23/l19 E Netherlands Primary Examiner-Joseph Scovronek [73] Assigneez U.S.Philips Corporation, New Anomey Frank R Trifari York, N.Y.

[22] Filed: Feb. 22, 1971 A device such as hot-gas engines, hot-gasturbine, and

[21] Appl. No.: 117,503

internal combustion engine for converting calorific energy intomechanical energy comprising at least one combustion chamber forhydrogen and at least one Foreign Application Priority Data Mar. 6, 1970Netherlands..................... ..700320l cooler incorporated in asystem of ducts for cooling medium; the combustion chamber can be madeto v mi r. at. .1 OCma a fm communicate with a hydrogen containereontainin alloy of A and B, in which the ratio A:B can va 1:3 to 2:17 inpowder form more of the elements of the rare earth with Th and/or Zrand/or Hf,

and/or Co. The hydrogen container and a l 5 1 l l6 ,1 A5 5 W0 21 12 6 M2 4 2 2 m5 1 W 4 1 system of ducts are constructed for heat exchangebetween the alloy in the hydrogen container and the [56] Reeremes C'tedmedium in the system of ducts.

5 Claims, 4 Drawing Figures UNITED STATES PATENTS PATENTEI] RAY I 5l975SHEET 1 OF 2 -t (min) INVENTOR.

MEU E R ROELF J.

PATENTEDKAY1 5197.5 3'. 782.690

SHEET 2 BF 2 IHUSUl INVENTOR. ROELF J. MEUER DEVllCE FOR CONVERTINGCALORIFIC ENERGY INTO MECHANICAL ENERGY The invention relates to adevice for converting calorific energy into mechanical energy, inparticular a hotgas engine, comprising at least one combustion chamberwhich communicates with at least one inlet duct for hydrogen, andfurthermore comprising at least one cooler which is incorporated in asystem of ducts for cooling medium, with a pumping device alsoincorporated in the system.

Devices of this type are known and they are formed, by hot-gas turbines,internal combustion engines and the like in addition to hot'gasreciprocating engine.

The system of ducts may form a closed circuit or an open circuit. In thefirst case a radiator is usually present between the inlet and theoutlet of the system of ducts. Cooling medium, for example water,circulated in the system of ducts by the pumping device absorbs in thecooler thermal energy to be removed from the device and delivers saidthermal energy subsequently in the radiator to the ambient air.

An open system of ducts is sometimes used on board vessels. In this casethe water of the fairway serves as a cooling medium which is sucked inby the pumping device, is conducted through the cooler where it absorbsthermal energy from the device, and is then exhausted in the fairwaywater as hot water.

The use of hydrogen as a fuel for the device is known from Dutch patentspecification 72,034 and presents the advantage that the exhaust gasesof. the device are clean due to the absence of unburnt hydrocarbons andcarbon monoxides which both are detrimental to health.

Notably, the use of hydrogen as a fuel is advantageous in hot-gasengines having a closed thermodynamic cycle, for example, hot-gasengines and hot-gas turbines, because in this case the quantity ofnitrogen oxides in the exhaust gases which are also detrimental tohealth is comparatively low. As compared, for example, with internalcombustion engines, the quantity of formed nitrogen oxides is at least afew factors lower.

As a result of this, such hydrogen-operated engines are extremelysuitable for use in places where pollution of air is to be minimized.

Such places include not only factory and storage spaces, mines, and thelike, in which the engine can be arranged stationary or is present as asource of energy in vehicles, and in which spaces special ventilationmeans are normally required owing to the air pollution, but also citieswith their large population concentrations and numerous vehiclesproducing gases which are detrimental to health.

A problem in the known device is the hydrogen supply. Vehicles, vesselsand air-craft equipped with engines or gas turbines which arehydrogen-operated have only a restricted range of action as a result ofthe comparatively small quantity of hydrogen which can be carried alongas a storage in a hydrogen tank. This is caused by the fact that: (a)the dimensions of the tank, for spatial reasons, should remainrestricted, and (b) the pressure of the hydrogen in the tank cannot beincreased arbitrarily high without the danger of explosion; to avoidthis danger would necessitate the use of extremely thick tank wallsresulting in a great weight of the tank.

The hydrogen tank should be refilled after a comparatively short time.Supplying the tank is a comparatively expensive and complicated matterbecause compressors should be used which either compress the hydrogenpreviously and force it into a high-pressure storage container fromwhich it can be conducted into the hydrogen tank at a later instant, orcompress lowpressure hydrogen and simultaneously force the compressedhydrogen into the hydrogen tank.

It is the object of the present invention to provide a device forconverting calorific energy into mechanical energy in which theabove-described drawbacks are avoided and in which the cooling system ofthe device is advantageously used both on filling the hydrogen tank andduring the discharge of hydrogen from the tank to the combustion chamberof the device during operation.

For that purpose, the device according to the invention is characterizedin that the side of the inlet duct for hydrogen remote from thecombustion chamber can be made to communicate with a hydrogen containerin which an alloy ofA and B is present in which the ratio A:B may varyfrom 1:3 to 2:17 in powder form, where A is Ca or one or more of theelements of the rare earths, possibly combined with Th and/or Zr and/orHf, and where B is mainly Ni and/or Co, the hydrogen container and apart of the system of ducts being suitable for exchanging thermal energybetween the alloy in the hydrogen container and the medium in the systemof ducts. It is to be noted that in connection with the presentapplication the element Y is assumed to be among the elements of therare earths.

It has surprisingly been found that the alloy AB has the property ofbeing capable of absorbing very large quantities of hydrogen gas at roomtemperatures and at comparatively low pressures. For example, 0.080 g ofhydrogen gas is absorbed by 1 cm LaNi powder having a packing density of65 percent at a hydrogen gas pressure of 5 atmospheres and at atemperature of approximately 40 C. The density of the hydrogen gas inthe alloys may be of the order of magnitude of that of liquid hydrogenand more.

isotherms can be drawn for each of the alloys associated with the groupAB in a diagram in which the hydrogen gas pressure P is plotted on thevertical axis and the absorbed quantity of hydrogen C is plotted on thehorizontal axis. At a given pressure, each isotherm has a horizontalcourse, the so-called plateau. At the plateau pressure it is possible,by means of a small pressure variation, to cause comparatively muchhydrogen gas to be absorbed or to be given off in a reversible process.

In the graph of FIG. 1 the course of the said isotherms is shown forLaNi The hydrogen gas can be absorbed very rapidly in the material andalso be recovered again very rapidly from the material.

The graph of FIG. 2 shows how at various working temperatures and at anoutside pressure of 1 atm. for LaNi the quantity of outflowed hydrogengas depends upon time. It is of great advantage when using saidmaterials in the device according to the invention that large quantitiesof hydrogen gas are absorbed at temperatures which lie at or near theroom temperature level, while the corresponding hydrogen pressures atthese temperatures are low and may be only a few atmospheres. This meansthat in a hydrogen container of small dimensions containing the alloy ABa large quantity of hydrogen can be stored at room temperature and at alow pressure.

In addition to savings in volume and weight of the hydrogen tank, aconsiderably larger range of action of vehicles, vessels and air-craftcomprising a hydrogenoperated source of energy is obtained in thismanner, while owing to the low hydrogen pressure in the container thedanger of explosion is minimized. Should in certain circumstancesleakage of the hydrogen container occur, the container will be cooled asa result of the flowing out of hydrogen to the atmosphere. The resultingfall in temperature of the container results in a decrease of thehydrogen pressure level in the container as can be seen from FIG. 1, sothat upon reaching atmospheric pressure the outflow of hydrogen isdiscontinued automatically. So the hydrogen container has a fineself-safeguarding effect. Filling of the container can be carried out atlow pressure, so that compressors are no longer necessary.

In addition, the device according to the invention advantageously usesits cooling system during the absorption and desorption of hydrogen inthe hydrogen container. For that purpose, a part of the system of ductsis suitable for exchanging heat between the alloy in the hydrogencontainer and the medium in the system of ducts. Upon filling thehydrogen container, said medium may be used as a cooling medium byabsorbing the heat of absorption released in the container and removingit, while during operation of the device the medium heated in the coolercan effectively be used for heating purposes by supplying the heat ofdesorption which is necessary for releasing hydrogen gas from the alloyin the container. In a closed system of ducts which comprises aradiator, said radiator may be constructed so as to be small becauseactually a part of the cooling medium thermal energy is delivered to thehydrogen container. Alternatively it is possible to increase theefficiency and power of the device by returning cooling water of lowertemperature to the device. By using means which are mainly presentalready, a simple, cheap and reliable construction for the hydrogenstorage and hydrogen discharge is obtained.

In a preferred embodiment of the device according to the invention, thehydrogen container contains one of the alloys LaNi La Y Ni La Zr ,Ni La,Ce, Ni,,, where 0.4 x I; XYNi where XY is an alloy comprising 85 percentby weight of La, per cent by weight of Nd, 4 percent by weight of Pr and1 percent by weight of Ce.

In particular these alloys have proved to possess extremely goodabsorbing and desorbing properties for hydrogen gas. It is to be notedthat Ni and/or Co can be partly replaced by a few other elements such asFe, Cu, and so on, without the properties as regards the absorption andgiving off of hydrogen gas strongly deteriorating.

In order that the invention may be readily carried into effect, twoembodiments of the device will now be described in greater detail withreference to the diagrammatic FIGS. 3 and 4 of the accompanying drawingwhich are not drawn to scale.

Reference numeral 1 in FIG. 3 denotes a hot-gas engine having a closedthermodynamic cycle.

The engine comprises a cooler 2 which is accommodated in an open systemof ducts 3 having a pumping device 4.

A part of the system of ducts has a widened construction. In thewidening 5 of a container 6 is accommodated which contains very finepowder of LaNi,,. The

container 6 can be made to communicate with a hydrogen supply via a duct7 which is passed through the wall of the widening and comprises a cock8. Via a further duct 9 which is also passed through the wall of thewidening and which comprises a cock 10 the container communicates with acombustion chamber 11 of the engine. An outlet 12 for exhaust gasescommunicates with the combustion chamberv The operation of the device isas follows: During operation of the engine, cooling water is pumpedthrough the system of ducts 3 by the pumping device 4 in the directiondenoted by the solid-line arrows. The cooling water absorbs thermalenergy from the engine in the cooler 2, delivers said thermal energy atleast partly in the widening 5 to the hydrogen container 6, and is thenremoved.

The thermal energy supplied to the hydrogen container is used to desorbhydrogen absorbed in the LaNi powder. When the hydrogen container isheated to a temperature of, for example, 40 C it may be seen from thegraph of FIG. 1 that the pressure in the container will be approximately5 atm. In the closed position of the cock 8 and the open position of thecook 10, hydrogen will flow from the container 6 via the duct 9 to thecombustion chamber 11 and be burnt there.

When the hydrogen container 6 is to be filled, the duct 7 is made tocommunicate with the hydrogen source and cock 8 is opened. The coolingwater system can now advantageously by used for removing from thehydrogen container the heat absorbed during operation. When the engineis not in operation, and with the pumping device not coupled to theshaft 13 of the engine but driven, for example, by means of an electricmotor, no further measures need be taken. When the cooling wateroriginating from the cooler 2 has such a high temperature that it cannotcool the hydrogen container during the filling process, the action ofthe pumping device may be reversed, for example, so that cooling wateris sucked in. This water first passes the widening 6, and onlysubsequently the engine. Of course, in addition to reversing the actionof the pumping device, a large number of other possibilities isavailable, so that during filling comparatively cold water flows throughthe widening 5. For example, a part of the sucked-in cooling water canbe conducted along the cooler via a bypass duct and be mixed with warmwater originating from the cooler, or a bypass duct in which a radiatoris present can be made to communicate with the part of the duct presentbetween the cooler 2 and the hydrogen container 6. During filling thehydrogen container, warm cooling water from the cooler 2 can beconducted through said radiator, can deliver thermal energy to theambient air, and enter the widening 5 while cooled. However, suchsolutions require extra structural measures.

The device shown in FIG. 4 differs essentially from that shown in FIG. 3only in that in the present case a closed cooling system is present inwhich the cooling water is circulated. A radiator 14 is incorporated inthe closed system of ducts. For corresponding components the samereference numerals are used as in FIG. 3.

During operation of the device, cooling water is circulated by thepumping device 4 in the direction dcnoted by the solid-line arrows.Thermal energy absorbed in the cooler 2 from the device is delivered bythe cooling water partly in the radiator 14 to the ambient air andpartly in the widening 5 to the hydrogen container 6. The'hydrogendesorbed by the heating of said container flows again via duct 9 to thecombustion chamber lll. When, for example, the hydrogen container isheated to C, the hydrogen pressure will be approximately 2.5 atmospheresas may be seen again from FIG. l. The cooling water originating from thewidening 5 then again arrives in the cooler 2 with alow temperature.

In the known closed cooling systems the radiator should be constructedrather large so as to be able to deliver all the thermal energy absorbedby the cooling water from the device in said radiator to the ambientair. Since in the present case a part of the thermal energy in thecooling water is used for desorbing hydrogen, the advantage ofa compactconstruction of the radiator 14 is obtained.

On the other hand it may be advantageous in the hotgas engine, tomaintain the comparatively large radiator. The cooling water from theradiator will then desorb the hydrogen at lower temperature and hence atlower hydrogen pressure from the LaNi Cooling water from the widening 5now enters the cooler 2at a lower temperature which favorably influencesthe efficiency and power of the hot-gasengine.

Since in the hot-gas engine the thermal energy absorbed by the coolingwater in the cooler is directly dependent upon the power suppliedby theengine, always so much thermal energy can be supplied to the hydrogencontainer as is necessary for the desorption of the quantity of hydrogento be supplied.

During the filling of the hydrogen container the cooling water, when theengineis not in operation, can be used again, as in the deviceshown inFIG. 3, to remove the releasing heat of absorption from said container.

If, however, the cooling water again has a comparatively hightemperature due:to operation of the engine, one of the measures may betaken which are mentioned in the description of the device shown in FIG.3, so as to ensure that the cooling water enters the widening 5 at acomparatively low temperature.

In the direction of flow of the cooling water denoted in FIG. 4 bysolid-line arrows, cooling water from the cooler 2 first flows throughthe radiator 14 and then through the widening 5. Of course it is alsopossible to cause the cooling water to circulate in the oppositedirection during operation of the engine. However, this is lessattractive on the one hand because the hydrogen container is heated. toa comparatively high temperature, which involves a comparatively highhydrogen pressure, and on the other hand because the temperaturedifference between the cooling water in the radiator 14 and the ambientair is comparatively small which is unfavorable for the heat delivery tosaid ambient air. The radiator must then be constructed to be largeagain so as to prevent cooling waterfrom reaching the engine in acomparatively warm state.

In the embodiments described, the hydrogen container is accommodated ina widening of the system of ducts. Of course other constructions arealso possible. For example, the system of ducts may be built up at theregion of the hydrogen container, for example, from a number of parallelpipes which are passed through the hydrogen container, the coolingmedium flowing through said pipes.

From the above, it may be obvious that the invention provides anextremely attractive hydrogen-operated device for converting calorificenergy into mechanical energy, in which a large quantity of hydrogen ata low pressure and at room temperature can be stored in a storagecontainer of small dimensions and in which the cooling system of'thedevice is efficiently used during the suppletion of hydrogen to thecombustion chamber of the device and upon filling the hydrogencontainer.

What is claimed is:

1. In combination with a hot gas engine including a combustion chamberand a cooler, and operable with a source of H and a source of heattransfer medium, a heating system comprising a container for H includinginlet and outlet means, means for flowing said H from the container tothe combustion chamber, means for flowing said medium from the sourcethereof to said cooler where the medium is heated, means for flowingsaid heated medium to said container for heating same, means for flowingsaid medium from the container to said source thereof, the containerhaving therein an alloy capable of absorbing large quantities of H gasat room temperature and at low pressures, said alloy consistingessentially of A and B where the ratio of A to B is about 1:3 to 2:17 inpowder form, and A is at least one element selected from the groupconsisting of calcium and the rare earth elements, and B is at least oneelement selected from the group consisting of Ni and Co, whereby saidalloy desorbs said H therein when heated by said medium, and H flows tosaid combustion chamber.

2. For use with a hot gas engine including a combustion chamber and acooler, and operable with a source of H and a source of heat transfermedium, a heating system comprising a container for H including inletand outlet means, means for flowing said I-l from the container to thecombustion chamber, the apparatus further comprising a radiator for heatexchange with ambient air, a closed duct system comprising means forflowing said medium to the cooler where it is heated and then to theradiator where it is partially cooled, and then to the container whereit is further cooled thus heating said container and contents therein,said container having therein an alloy capable of absorbing largequantities of H gas at room temperature and at low pressures, said alloyconsisting essentially of A and B where the ratio ofA to B is about 1:3to 2:17 in powder form, and A is at least one element selected from thegroup consisting of calcium and the rare earth elements, and B is atleast one element selected from the group consisting of Ni and Co,whereby said alloy desorbs saidH therein when heated by said medium, andH flows to said combustion chamber.

3. Apparatus according to claim 2 wherein said closed duct systemcomprises a plurality of ducts interconnecting said cooler, saidcontainer, and said radiator in a closed system.

4. For use with a device for converting calorific energy into mechanicalenergy including a combustion chamber and a cooler, and operable with asource of H and a source of heat transfer medium, a heating systemcomprising a container for H including inlet and outlet means, means forflowing said H from the container to the combustion chamber, means forflowing said medium from the source thereof to said cooler where themedium is heated, means for flowing said heated medium to said containerfor heating same, means for flowing said medium from the container tosaid source thereof, the container having therein an alloy capable ofabsorbing large quantities of H gas at room temperature and at lowpressures, said alloy consisting essentially of A and B where the ratioof A to B is about 1:3 to 2:17 in powder form, and A is at least oneelement selected from the group consisting of calcium and the said alloydesorbs said H therein when heated by said medium, and H flows to saidcombustion chamber.

5. Apparatus according to claim 4 wherein said alloy contains inaddition at least one element selected from rare earth elements, and Bis at least one element se- 5 the group consisting of Th, Zr, and Hf.

lected from the group consisting of Ni and Co, whereby

2. For use with a hot gas engine including a combustion chamber and acooler, and operable with a source of H2 and a source of heat transfermedium, a heating system comprising a container for H2 including inletand outlet means, means for flowing said H2 from the container to thecombustion chamber, the apparatus further comprising a radiator for heatexchange with ambient air, a closed duct system comprising means forflowing said medium to the cooler where it is heated and then to theradiator where it is partially cooled, and then to the container whereit is further cooled thus heating said container and contents therein,said container having therein an alloy capable of absorbing largequantities of H2 gas at room temperature and at low pressures, saidalloy consisting essentially of A and B where the ratio of A to B isabout 1:3 to 2:17 in powder form, and A is at least one element selectedfrom the group consisting of calcium and the rare earth elements, and Bis at least one element selected from the group consisting of Ni and Co,whereby said alloy desorbs said H2 therein when heated by said medium,and H2 flows to said combustion chamber.
 3. Apparatus according to claim2 wherein said closed duct system comprises a plurality of ductsinterconnecting said cooler, said container, and said radiator in aclosed system.
 4. For use with a device for converting calorific energyinto mechanical energy including a combustion chamber and a cooler, andoperable with a source of H2 and a source of heat transfer medium, aheating system comprising a container for H2 including inlet and outletmeans, means for flowing said H2 from the container to the combustionchamber, means for flowing said medium from the source thereof to saidcooler where the medium is heated, means for flowing said heated mediumto said container for heating same, means for flowing said medium fromthe container to said source thereof, the container having therein analloy capable of absorbing large quantities of H2 gas at roomtemperature and at low pressures, said alloy consisting essentially of Aand B where the ratio of A to B is about 1:3 to 2:17 in powder form, andA is at least one element selected from the group consisting of calciumand the rare earth elements, and B is at least one element selected fromthe group consisting of Ni and Co, whereby said alloy desorbs said H2therein when heated by said medium, and H2 flows to said combustionchamber.
 5. Apparatus according to claim 4 wherein said alloy containsin addition at least one element selected from the group consisting ofTh, Zr, and Hf.